JP4542347B2 - Thermoplastic polyurethane and use thereof - Google Patents

Description

  The present invention relates to a thermoplastic polyurethane (hereinafter simply referred to as “polyurethane”) having a high rebound resilience particularly used for a golf ball cover material and having a small change in rebound resilience due to a temperature change, and molding using the same. Relates to the composition.

  Polyurethane has high strength and has excellent properties such as wear resistance and flex resistance, and has been used for applications such as pressure-resistant hoses, packing, conveyor belts and shoe soles. On the other hand, in the field of golf balls, in recent years, multi-piece golf balls (hereinafter sometimes referred to simply as “golf balls”) are often used in view of spin characteristics, flying performance, feel at impact, durability, and mass productivity. Polyurethane has been used as a cover material (see Patent Documents 1 to 4). However, polyurethane used as a cover material for conventional golf balls does not have a very large rebound resilience, and the change in rebound resilience due to temperature is large, particularly when the outside air temperature is low. There is a drawback that it decreases, and there is a demand for a solution to these problems.

Japanese Patent Laid-Open No. 6-182002 Japanese Patent Laid-Open No. 9-271538 Japanese Patent Laid-Open No. 11-178949 Japanese Patent Laid-Open No. 11-253580

  Accordingly, an object of the present invention is to provide a polyurethane, particularly a golf ball cover material, in which the above disadvantages of conventional polyurethanes are improved.

As a result of various studies to achieve the above object, the present inventors used 1,4-bis (hydroxyethoxy) benzene (hereinafter referred to as “BHEB”) as a low molecular weight diol together with a high molecular weight diol in the production of polyurethane. It has been found that polyurethane has a high rebound resilience and has a small decrease in rebound resilience in a low temperature range, that is, a change in rebound resilience due to a change in outside air temperature is small. The present invention has been completed.
The above object is achieved by the present invention described below. That is, in the present invention, segment A composed of a high molecular weight diol, segment B composed of BHEB as a low molecular weight diol, and segment C composed of polyisocyanate are linearly bonded by urethane bonds. The segment A includes the segment E composed of polysiloxane diol or modified polysiloxane diol, and the amount of the segment B accounts for 1 to 30% by mass in the polyurethane. There is provided a polyurethane for a golf ball cover material.

In the above-described present invention, furthermore, preferably a child contain segments D constructed from low molecular weight diols other than BHEB.

In the present invention, the high molecular weight diol is a number average molecular weight of 600 to 4, selected from the group consisting of polytetramethylene ether glycol (hereinafter referred to as “PTMG”), polybutylene adipate diol, polycarbonate diol and polysiloxane diol. The low-molecular-weight diol is BHEB, the polyisocyanate is 4,4′-diphenylmethane diisocyanate (hereinafter referred to as “MDI”), and the proportion of these components used is 100 parts by mass of the high-molecular-weight diol. Polyurethanes having a low molecular weight diol of 10 to 120 parts by mass and a polyisocyanate of 20 to 170 parts by mass are useful for golf ball cover materials .

In the present invention, the high molecular weight diol is PTMG having a number average molecular weight of 1,000 to 2,000, the low molecular weight diol is BHEB, the polyisocyanate is MDI, and the proportions of these components used are Polyurethanes having a high molecular weight diol of 100 parts by weight, a low molecular weight diol of 11 to 42 parts by weight, and a polyisocyanate of 39 to 76 parts by weight are useful for golf ball cover materials .

  In the present invention, the high molecular weight diol is PTMG having a number average molecular weight of 800 to 1,200, the low molecular weight diol is BHEB, the polyisocyanate is MDI, and the use ratio of these components is high. Polyurethanes having a molecular weight diol of 100 parts by weight, a low molecular weight diol of 20 to 30 parts by weight, and a polyisocyanate of 50 to 60 parts by weight are particularly suitable for golf ball cover materials.

  The polyurethane of the present invention has a rebound elastic modulus at 23 ° C. of 50 to 90%; and the rebound elastic modulus at 0 ° C. is 0.6 times or more of the rebound elastic modulus at 23 ° C. Sometimes it is particularly suitable for golf ball cover materials.

  ADVANTAGE OF THE INVENTION According to this invention, a polyurethane which has a high rebound resilience and a rebound resilience is not influenced by external temperature (the change of rebound resilience due to a temperature change is small) is provided. The polyurethane is particularly useful as a cover material for golf balls.

  Next, the present invention will be described in more detail with reference to the best mode for carrying out the preferred invention. The polyurethane of the present invention is useful for various applications, but is particularly useful as a golf ball cover material. Therefore, a golf ball cover material will be described below as a representative example of the application.

  The present invention relates to a polyurethane for a cover material which forms a cover of a golf ball comprising a core and a cover, and the polyurethane is synthesized using BHEB and / or 1,3-propanediol as a low molecular weight diol of a polyurethane synthesis raw material. It is characteristic that it is.

  The golf ball has a structure in which a core made of a cis 1,4-polybutadiene cross-linked product having excellent rebound resilience is covered with a cover made of a cover material such as polyurethane, and a two-piece golf made up of a core and a single cover. A ball or a three-piece golf ball having a two-layer cover that is further covered with a ball is used. The polyurethane of the present invention is useful as a cover material for forming the cover of the golf ball as described above.

  Polyurethane is usually obtained by reacting a high molecular weight diol with a polyisocyanate, but the polyurethane of the present invention contains BHEB and / or 1,3-propanediol together with a high molecular weight diol and 1,4-butanediol as necessary. It is obtained together with other low molecular weight diols and reacted with polyisocyanate. A particularly preferred low molecular weight diol among BHEB and 1,3-propanediol is BHEB.

  The polyurethane of the present invention can be expressed, for example, as a repeating unit of the formula {-(A-C-B-C-B)-}. Where A represents a segment composed of high molecular weight diol, B represents a segment composed of BHEB and / or 1,3-propanediol, and C represents a segment composed of polyisocyanate, These segments are connected by urethane bonds. In the present invention, the segment B is present in the polyurethane in an amount of 1 to 30% by mass. In addition, the said formula is an illustration and changes with the kind and quantity of the raw material used at the time of manufacture of a polyurethane.

  As the high molecular weight diol constituting the segment A in the present invention, any known ones conventionally used for the production of polyurethane can be used, but the number average molecular weight (by end group determination method) is 1,000 to 10,000. 000 is preferred. Examples of the high molecular weight diol include polyester diol, polyether diol, polycarbonate diol, polylactone diol, and polysiloxane diol.

  Examples of the polyester diol include dibasic acids (for example, succinic acid, glutaric acid, adipic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, tartaric acid, oxalic acid, malonic acid, pimelin. Acid, suberic acid, glutaconic acid, azelaic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, etc.) Or an anhydride thereof and a glycol (for example, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1 , 3-butanediol, 1,4- Aliphatic glycols such as tandiol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol; Alicyclic glycols such as bishydroxymethylcyclohexane and cyclohexane-1,4-diol; aromatic glycols such as xylylene glycol) or C1 to C18 alkyldiethanolamine, etc. Examples thereof include condensed polyester diols such as polyethylene adipate diol, polybutylene adipate diol, and polyhexamethylene adipate diol.

  Examples of the polylactone diol include lactone polyester diols such as polylactone diol, polycaprolactone diol, and polymethylvalerolactone diol obtained by ring-opening polymerization of lactone using the diol as an initiator.

Examples of the polyether diol include homopolyether diols of alkylene oxides such as PTMG, polyethylene ether glycol, and polypropylene ether glycol, and copolyether diols of different types of alkylene oxides.
Examples of the polycarbonate diol include poly 1,6-hexane carbonate diol and poly 1,4-butylene carbonate diol.

（上記式中の、Ｒ^1a〜Ｒ^1hは各々独立して、炭素数１〜８のアルキル基またはアリール基を、Ｒ^2a〜Ｒ^2cは各々独立して、アルキレン基あるいはエステル結合もしくはエーテル結合を有する二価の置換基を、ｎは１〜３００程度の整数をそれぞれ表す。） In the present invention, it is preferable to use polysiloxane diol as part or all of the high molecular weight diol. Known polysiloxane diols can be used, and examples thereof include polysiloxane diols represented by the following general formulas (I), (II) and (III). These polysiloxane diols constitute segment E in the polyurethane of the present invention.

(In the above formulas, R ^1a to R ^1h are each independently an alkyl group or an aryl group having 1 to 8 carbon atoms, R ^2a to R ^2c are each independently an alkylene group or an ester bond or ether bond (Wherein n represents an integer of about 1 to 300).

Specific examples of the polysiloxane diol as described above include, for example, the following polysiloxane diol.

  In the present invention, BHEB and / or 1,3-propanediol is used as a low molecular weight diol together with the above high molecular weight diol in the production of polyurethane. If necessary, in addition to the low molecular weight diol, other low molecular weight diols are used. Can be used in combination. The other low molecular weight diol constitutes the segment D of the polyurethane of the present invention.

  As the other low molecular weight diols, any of known low molecular weight diols conventionally used in the production of polyurethane can be used, but those having a number average molecular weight (by end group determination method) of 250 or less are preferable. For example, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Aliphatic glycols such as pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,9-nonanediol, neopentylglycol, bishydroxymethylcyclohexane, Examples include alicyclic glycols such as cyclohexane-1,4-diol and aromatic glycols such as xylylene glycol.

  The amount of BHEB and / or 1,3-propanediol used is an amount such that the segment B composed of these diols is 1 to 30% by mass in the obtained polyurethane, more preferably 5 to 25% by mass. This is the amount. If the amount of these segments B is too small, the hardness of the resulting polyurethane is too low, while if too large, the resilience modulus of the resulting polyurethane is low. Further, when BHEB and / or 1,3-propanediol is used in combination with other low molecular weight diol, the ratio of BHEB and / or 1,3-propanediol is 30 to 100 mass in the total amount of low molecular weight diol. %, Preferably 65 to 100% by mass. When the ratio of BHEB and / or 1,3-propanediol is less than 30% by mass, the resulting polyurethane has low impact resilience, and when it is 65% by mass or more, the resulting polyurethane has high resilience, which is preferable.

  As the polyisocyanate used in the present invention, any conventionally known polyisocyanate can be used and is not particularly limited. For example, 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, lysine methyl ester diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 1,5-octylene diisocyanate, dimer acid diisocyanate Aliphatic isocyanates such as 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate; 4- or 2,6-tolylene diisocyanate (TDI), MDI, 1,5-naphthylene diisocyanate DOO, xylylene diisocyanate (XDI), triphenylmethane triisocyanate, tris (4-phenylisocyanate) thiophosphate, tolidine diisocyanate, p- phenylene diisocyanate, diphenyl ether diisocyanate, and the like aromatic isocyanates, such as diphenyl sulfone diisocyanate.

  The polyurethane of the present invention can be obtained by reacting each of the above-mentioned components, but the production method can use a conventionally known polyurethane production method, and the use ratio of both the high molecular weight diol and the low molecular weight diol and the polyisocyanate is as follows. The equivalent ratio of NCO / OH is preferably in the range of 0.95 to 1.10.

  Among the polyurethanes of the present invention, the high molecular weight diol is at least one of a number average molecular weight of 600 to 4,000 selected from the group consisting of PTMG, polybutylene adipate diol, polycarbonate diol and polysiloxane diol, and a low molecular weight diol BHEB, polyisocyanate is MDI, and the proportion of these components used is 100 parts by mass of high molecular weight diol, 10 to 120 parts by mass of low molecular weight diol, and 20 to 170 parts by mass of polyisocyanate. It is useful for molding products.

  Among the polyurethanes of the present invention, the high molecular weight diol is PTMG having a number average molecular weight of 1,000 to 2,000, the low molecular weight diol is BHEB, the polyisocyanate is MDI, and the use of these components Polyurethanes having a proportion of 100 parts by mass of high molecular weight diol, 11 to 42 parts by mass of low molecular weight diol, and 39 to 76 parts by mass of polyisocyanate are useful for molding various molded products including golf ball cover materials.

  Moreover, among the polyurethanes of the present invention, the high molecular weight diol is PTMG having a number average molecular weight of 800 to 1,200, the low molecular weight diol is BHEB, the polyisocyanate is MDI, and the use ratio of these components is Polyurethanes having a high molecular weight diol of 100 parts by weight, a low molecular weight diol of 20 to 30 parts by weight, and a polyisocyanate of 50 to 60 parts by weight are particularly useful as a golf ball cover material.

  The polyurethane of the present invention described above preferably has a resilience modulus at 23 ° C. of 50 to 90%. When the rebound resilience at 23 ° C. is less than 50%, golf balls made using the polyurethane as a cover material do not fly well, and when it exceeds 90%, it is difficult to synthesize the polyurethane itself. The polyurethane of the present invention preferably has a ratio of the rebound resilience at 0 ° C. to the rebound resilience (Rb) at 23 ° C. (Rb (0 ° C.) / Rb (23 ° C.)) of 0.60 or more. . If this ratio is less than 0.60, the flying distance and feel at impact of a ball made using the polyurethane as a cover material differ greatly depending on whether the outside air temperature is high or low. Furthermore, the hardness of the polyurethane of the present invention measured according to JIS K7311 is preferably in the range of JIS A60 to JIS D80.

  The polyurethane of the present invention is particularly used as a cover material for a multi-piece golf ball, but can also be used as an intermediate layer forming material for a multi-piece golf ball comprising a core, an intermediate layer, and a cover. When the polyurethane of the present invention is used as a golf ball cover material, the polyurethane of the present invention can be used as a main component, and if necessary, other polymer components can be used in combination as a molding composition. You may mix | blend additives, such as a coloring agent, antioxidant, an ultraviolet-ray inhibitor, and a mold release agent used conventionally.

  As described above, the use of the polyurethane of the present invention has been described using a golf ball cover material as a representative example. However, the use of the polyurethane of the present invention is not limited to a golf ball cover material. For example, gears, packing, rollers, casters, high It is also useful as a material for industrial parts such as repulsion tubes, high repulsion hoses, electric wire coatings, high repulsion belts, high repulsion films, sports equipment such as sports shoes and bowling pins.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “part” or “%” is based on mass unless otherwise specified.
In addition, the strength characteristics and hardness of the polyurethanes of Examples and Comparative Examples were measured with a Lupke type test apparatus according to JIS K7311 and the rebound resilience according to JIS K7311. In addition, the flow characteristics are in accordance with JIS K7311 under the conditions of a nozzle of 1 mm (diameter) × 10 mm (length), a load of 4.9 MPa (50 kgf / cm ² ), and a temperature increase rate of 3 ° C./min. It was measured.

Example 1
To 1,000 parts of polybutylene adipate diol having a number average molecular weight of 2,000, 196 parts of BHEB and 387 parts of MDI were uniformly stirred and poured into a tray and reacted at 110 ° C. The obtained reaction product was pulverized and then pelletized at 200 to 230 ° C. using an extruder to obtain polyurethane (U1) pellets. This pellet was processed into a test piece by injection molding (the same applies to the following examples and comparative examples), and the hardness, strength characteristics (23 ° C.), flow characteristics and rebound resilience (0 ° C., 23 ° C.) were measured. The measurement results are shown in Table 1.

(Example 2)
Into 1,000 parts of PTMG having a number average molecular weight of 1,700, 178 parts of BHEB and 401 parts of MDI were uniformly stirred, poured into a tray and reacted at 110 ° C., and pelletized polyurethane in the same manner as in Example 1 below. (U2) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

(Example 3)
To 1,000 parts of polyε-caprolactone diol having a number average molecular weight of 2,000, 200 parts of BHEB and 393 parts of MDI were uniformly stirred, poured into a tray and reacted at 110 ° C., and the same as in Example 1. As a result, pelletized polyurethane (U3) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

Example 4
To 1,000 parts of hexamethylene carbonate diol having a number average molecular weight of 2,000, 189 parts of BHEB and 378 parts of MDI were uniformly stirred, poured into a tray and reacted at 110 ° C., and the same as in Example 1 below. Pelletized polyurethane (U4) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

(Example 5)
Ester modification with a number average molecular weight of 5,200 and a siloxane content of 60% obtained by copolymerizing an alcohol-modified siloxane oil (KF-6002; manufactured by Shin-Etsu Chemical Co., Ltd.) having the following structure with a number average molecular weight of 3,200 and ε-caprolactone. Into 1,000 parts of polysiloxane diol and 450 parts of PTMG having a number average molecular weight of 1,700, 258 parts of BHEB and 514 parts of MDI were uniformly stirred, poured into a tray and reacted at 110 ° C. In the same manner as above, pelletized polyurethane (U5) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

(Comparative Example 1)
In 1,000 parts of PTMG having a number average molecular weight of 1,700, 111 parts of 1,4-butanediol and 474 parts of MDI were uniformly stirred, poured into a tray and reacted at 100 ° C., and the same as in Example 1 Thus, a pelletized polyurethane (U6) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

(Comparative Example 2)
In 1,000 parts of polybutylene adipate diol having a number average molecular weight of 2,000, 153 parts of 1,4-butanediol and 573 parts of MDI were uniformly stirred and poured into a tray and reacted at 100 ° C. In the same manner as in Example 1, pelletized polyurethane (U7) was obtained. Table 1 shows the measurement results of various properties of this polyurethane.

  From the results of Table 1, in the polyurethanes (U1 to U5) containing BHEB of Examples 1 to 5 in the range of 1 to 30%, the resilience elastic modulus is 50 to 90% at 23 ° C and the resilience at 0 ° C. It can be seen that the elastic modulus is not less than 0.60 times the rebound resilience at 23 ° C. and has a high rebound resilience that is not affected by changes in the outside air temperature, and is suitable as a cover material for a golf ball. On the other hand, in the polyurethanes (U6, U7) containing no BHEB of Comparative Examples 1 and 2, the rebound resilience at 23 ° C. is small at 50% or less, and the rebound resilience at 0 ° C. is the rebound resilience at 23 ° C. It is 0.60 times or less, and it can be seen that the resilience elastic modulus is greatly affected by the change in the outside air temperature and is inappropriate as a cover material for a golf ball.

(Example 6)
In 1,000 parts of polybutylene adipate diol having a number average molecular weight of 2,000, 124 parts of 1,3-propanediol and 554 parts of MDI were uniformly stirred and injected into a tray to react at 100 ° C. In the same manner as in Example 1, pelletized polyurethane (U8) was obtained. Table 2 shows the measurement results of various properties of this polyurethane.

(Example 7)
To 1,000 parts of PTMG having a number average molecular weight of 1,700, 98 parts of 1,3-propanediol and 487 parts of MDI are uniformly stirred, poured into a tray and reacted at 100 ° C., and the same as in Example 1 below. Pelletized polyurethane (U9) was obtained. Table 2 shows the measurement results of various properties of this polyurethane.

(Example 8)
To 1,000 parts of poly ε-caprolactone diol having a number average molecular weight of 2,000, 105 parts of 1,3-propanediol and 490 parts of MDI are uniformly stirred, poured into a tray and reacted at 100 ° C. In the same manner as in Example 1, pelletized polyurethane (U10) was obtained. Table 2 shows the measurement results of various properties of this polyurethane.

Example 9
In 1,000 parts of hexamethylene carbonate diol having a number average molecular weight of 2,000, 113 parts of 1,3-propanediol and 515 parts of MDI were uniformly stirred, poured into a tray and reacted at 100 ° C. In the same manner as in Example 1, pelletized polyurethane (U11) was obtained. Table 2 shows the measurement results of various properties of this polyurethane.

(Example 10)
Esters with a number average molecular weight of 3,200 and a number average molecular weight of 5,200 obtained by copolymerizing an alcohol-modified siloxane oil (KF-6002; manufactured by Shin-Etsu Chemical Co., Ltd.) having the following structure with a number average molecular weight of 3,200 and a siloxane content of 60% To 1,000 parts of modified polysiloxane diol and 450 parts of PTMG having a number average molecular weight of 1,700, 190 parts of 1,3-propanediol and 827 parts of MDI are uniformly stirred and poured into a tray and reacted at 100 ° C. In the same manner as in Example 1, pelletized polyurethane (U12) was obtained. Table 2 shows the measurement results of various properties of this polyurethane.

  From the results of Table 2, in the polyurethane (U8 to U12) containing the segment B composed of 1,3-propanediol of Examples 6 to 10 in the range of 1 to 30%, the resilience modulus is 50 to 50 at 23 ° C. The golf ball cover has a high rebound resilience that is 90% and the rebound resilience at 0 ° C. is 0.60 or more times the rebound resilience at 23 ° C. and is not affected by changes in the outside air temperature. It turns out that it is suitable as a material.

  According to the present invention as described above, a polyurethane having a high rebound resilience and having a rebound resilience that is not affected by the outside air temperature (a change in the rebound resilience due to a temperature change is small) is provided. The polyurethane can be used for various applications and is particularly useful as a cover material for golf balls.

Claims (7)

Segment A composed of a high molecular weight diol, segment B composed of 1,4-bis (hydroxyethoxy) benzene as a low molecular weight diol, and segment C composed of polyisocyanate are linear by urethane bonds. The segment A includes a segment E composed of a polysiloxane diol or a modified polysiloxane diol, and the amount of the segment B is 1 in the thermoplastic polyurethane. Thermoplastic polyurethane for golf ball cover material characterized by occupying ˜30 mass%.   The thermoplastic polyurethane for a golf ball cover material according to claim 1, further comprising a segment D composed of a low molecular weight diol other than 1,4-bis (hydroxyethoxy) benzene.   The high molecular weight diol is at least one selected from the group consisting of polytetramethylene ether glycol, polybutylene adipate diol, polycarbonate diol and polysiloxane diol, and the low molecular weight diol is 1,4. -Bis (hydroxyethoxy) benzene, polyisocyanate is 4,4'-diphenylmethane diisocyanate, and the proportion of these components used is 100 parts by mass of high molecular weight diol, 10 to 120 parts by mass of low molecular weight diol, and polyisocyanate 20 The thermoplastic polyurethane for a golf ball cover material according to claim 1, wherein the thermoplastic polyurethane is ˜170 parts by mass.   The high molecular weight diol is polytetramethylene ether glycol having a number average molecular weight of 1,000 to 2,000, the low molecular weight diol is 1,4-bis (hydroxyethoxy) benzene, and the polyisocyanate is 4,4′-diphenylmethane. The heat for golf ball cover material according to claim 1, which is diisocyanate, and the proportion of these components used is 100 parts by mass of high molecular weight diol, 11 to 42 parts by mass of low molecular weight diol, and 39 to 76 parts by mass of polyisocyanate. Plastic polyurethane.   The high molecular weight diol is polytetramethylene ether glycol having a number average molecular weight of 800 to 1,200, the low molecular weight diol is 1,4-bis (hydroxyethoxy) benzene, and the polyisocyanate is 4,4′-diphenylmethane diisocyanate. 2. The thermoplastic polyurethane for a golf ball cover material according to claim 1, wherein the use ratio of these components is 100 parts by mass of a high molecular weight diol, 20 to 30 parts by mass of a low molecular weight diol, and 50 to 60 parts by mass of a polyisocyanate. .   2. The thermoplastic polyurethane for a golf ball cover material according to claim 1, wherein the resilience modulus at 23 ° C. is 50 to 90%.   2. The thermoplastic polyurethane for a golf ball cover material according to claim 1, wherein a resilience modulus at 0 ° C. is 0.6 times or more of a resilience modulus at 23 ° C. 3.